Convertible alkyd resins



.utilized in forming the resin.

Patented Aug. 31, 1948 UNITED STATES PATENT OFFICE CONVERTIBLE ALKYD BESINS Theodore W. Evans, Oakland, and David E..Adelson, Berkeley,Calii'., assignore to Shell Development Company, San Francisco, Calif.,a corporation of Delaware ud Drawing. Application September 14,1945,

' Serial No. 010,414

16 Claims. 1

This invention relates to a class 01' alkyd resins which are both heatand oxygen convertible. More particularly, the invention pertain toalkyd resins from a class of unsaturated ethers of glycerol or'glycid-oland a dicarboxyllc acid or acid anhydride.

Alkyd resins are primarily complex esters from polyhydric alcohols andpolybaslc carboxylic acids and have been produced with widely varyingproperties. The variation in properties is largely dependent upon theparticular type of reactants theirnature and properties, the alkydresins are classified broadly into three general groups.

The alkyds of group I are termed non-convertible and are derived fromtwo reactants while being devoid of other modifiers, each of thesereactants being bi-functional. A resin of this type is obtainable from aglycol which contains two functional hydroxy group and a dicarboxylic'acid containing two acid groups. The resins from these reactants havemolecules which are linear in character and since no cross linkage ispossible, no three dimensional molecules are obtainable to give a resinwhich is convertible by heat or oxygen to an insoluble and infusiblestate.

The alkyds of group II are termed heat-c'onvert-ible and are obtainablefrom reactants at least one of which has a functionality greater thantwo. A classic example of an alkyd resin of this type is that fromglycerol and phthalic acid or anhydride. By esterifying glycerol .withphthalic acid or acid anhydride, a resin product is first obtained whichis both fusible and soluble in a number of solvents. The resin in thisstate is known as the A form in being both fusible and soluble.

. 'acid to which has been added a drying oil acid.

Dependent upon v By further heating the resin the B form is obtainedwhich is a gel and is fusible, but insoluble. Additional heatingconverts the B form to the C form which is both inf usible andinsoluble. Resins of this type are known as heat-convertible alkyds forthe reason that the fusible and soluble resin (A form) which isconvenient for handling in applications thereof, upon being heated, isconverted to the infusible and insoluble resin (C form).

The resins of group III'are known as oxygen- The presence of the dryingoil residue in the molecules enables oxygen to convert the resin to aninfusible and insoluble state probably by oxygen linkage.

An object of thepresent invention is to provide a new class of alkydresins.

Another object of the invention is to provide a class of alkyd resinswhich are both heat and oxygen convertible.

A further object of the invention is to provide a method of preparingsuch resins.

These and other objects of the invention will be apparent from thedescription given hereinafter.

We have discovered that alkyd resins which are convertible either byheat or oxygen or both, are 1 obtainable by reacting an unsaturated'ether of 'reaction which requires somewhat elevated temperatures. Byuse of a particular class of unsaturated ethers, we have found that thedesired fusible and soluble form of the alkyd can be obtained withoutcoupling occurring through the.

unsaturated ether group during the esterification although the resin issubsequently convertible by the action of heat or oxygen. The class ofunsaturated ethers of glycerol or glycidol which are neither toounstable for preparation of the alkyd, nor too stable so as to preventsubsequent conversion, are those having an olefinic bond in a particularposition. Theselcompounds are monoalkenyl ethers of glycerol or glycidolwherein the alkenyl group contains 3 to- 6 carbon atoms and convertibleor air-drying alkyd since they areconverted to the infusible andinsoluble state by contact with oxygen such as air. Resins. of. thistype may be prepared from glycerol and phthalic has an oleflnic linkagebetween two carbon atoms. one of which is the carbon atom of a terminalmethylene group and the other of which is linked directly to a saturatedcarbon atom having the ethereal oxygen atom linked directly thereto.Preferably, the alkenyl group is one represented by the formula alkydresins of the invention include such glycerol mono-others as allyl,methallyl, 2-chlorallyl, 3-

chlorallyl, ethallyl, propallyl and l-sopropallyl as well as lesspreferred types like methyl vinyl carbinyl, ethyl vinyl carbinyl, propylvinyl carbinyl,

dimethyl vinyl carbinyl, methyl isopropenyl car-" binyi, dimethylisopropenyl carbinyl, ethyl isopropenyl carblnyl, methyl butenylcarbinyl, etc. A mixture of two or more ethers can be used, if

desired. i

The corresponding glycidol unsaturated ethers can also be used asreactants, if desired, and are to be preferred in some respects, one ofwhich is that one less molecule of water need be removed in theesteriflcation involved in the formation of the resin. The unsaturatedradical in the glycidyl ethers can be the same as those illustrated inthe iqregoing for the glycerol ethers. Such unsaturated glycidyl2,314,039.

In forming the resin of the invention, the glycerol unsaturated ether orthe corresponding glycidol unsaturated ether is reacted with adicarboxylic acid or the corresponding acid anhy dride. Any dicarboxylicacid or acid anhydride is suitable although the properties of the resinwill vary somewhat depending upon the particular compound. used.As-examples of typical com-. pounds are oxalic acid, malonicacid,succinic acid, glutaric acid. adipic acid. sebacic acid, maleic acid;isosuccinic acid, fumaric .acid, phthali'c acid, tetra hydrophthallcacid, terephthalic acid, naphthalenedicarboxylic acid, diglycollic acid,dithioglycollic acid, dilactic acid, as well as the corresponding acidanhydrides. The acid anhydrides are preferred reactants though in someinstances they are non-existent substances such as inthe case withiumaric acid anhydride and the free acid must necessarily be used. I Thealkyd resinsof the present invention which are obtained from anunsaturated ether of glycethers are described in .U. B.

erol or glycldol are distinct in structure and diiresin prepared byheating a polybasic acid with a saturated alcohol or allyl alcohol andthen adding glycerol to the reaction mixture for completion of thereslniflcation process, the'monohydric aicohol being used .in place ofpart of the glycerol of the glycerol-polybasic acid alkyd resin. Theresins of the patentee are'heat-convertible owin to the use of glycerolwhich is a tri-functicnal reactant while the improved alkyd resins ofthe present invention are both heat and oxygen conyertible owing to theunsaturated group being linked by an ethereal oxygen atom to the resinmolecule. Further the alkyd resins known to the art which are preparedfrom glycerol alkyl ethers are not convertible while those of. thepresent in- 4 vention are rendered ini'usible and insoluble by heatingor contacting with oxygen because of the presence of the unsaturatedgroups ethereally linked to th resin molecule.

In effecting the resinification process a mixture I of the etherreactant and acid reactant is heated in. an'inert atmosphere. By aninert atmosphere is meant one substantially devoid of oxygen such as anatmosphere of nitrogen, carbon dioxide, helium, methane, or the like.'Ihereaction mixture is heatedto effect the desired reactions at atemperature of about to 250 C. I! desired the cooking may be startedwith a low tempera- .ture and gradually increased. It is ordinarilypreferable to eiiect the resinification with a tem' perature maintainedbelow about 200 0. since too high temperatures are prone to causediscoloration of the resin.

The preparation of reactants can be varied to considerable extentdepending upon the properties desired in the finished product.Ordinarily equ'imolecular amounts of ether reactant and acid reactantare suitable although excellent results are obtained with 10 to 20%excess of the other reactant and, when an excess of one reactant overthe other is used, it is usually desirable to employ an excess of theether reactant.

Since the alkyd resin is heat-convertible, care is required during theresiniflcation operation to avoid converting the resin to a step beyondthat of being fusible and soluble. This will occur if the reactionmixture is over-cooked. To avoid such difliculty. the course of theresiniflcation is conveniently followed by making determinations of theacid number upon samples withdrawn from the reaction mass or by otherwell known methods. Ordinarily the heating is continued until the acidnumber has been reduced to a value of about 10 to 40. Another expedientuseful for preventing gel formation, is the use of small amounts up to25% of a diluent such as a hydrocarbon like kerosene.

For the purpose of further illustrating the method of preparing theconvertible alkyd resin and some of its properties, the followingexamples are givenwherein the use of the most preferred reactants aredescribed, but it is to be under-. stood that the invention is not to beconstrued as limited to any specific details given therein.

Example I About 2 6.4'parts of glycerol allyl ether and 29.0 parts ofphthalic anhydride were placed in a es. sel fitted in an oil bathmaintained at about 180 C. Nitrogen was bubbled through the reactionmass during the heating for the purpose of agitatingit and carrying oilvolatile products as well as to'maintain an inert atmosphere over it.After 18 hours heating at 180 0., the product was still liquid withlittle more body than at the start, but had turned amber in color. Afterabout 26 hours, the reaction mass had considerable mass and a drop ofthe resin would solidify on cooling to room temperature. A determinationgave a value of 3-1 for the acid number after 31 hours heating. Theheating was discontinued after '51 hours and it was found that the acidnumber had been reduced to about 10.5. The product was a very viscous.dark brown mass.

Example If A portion of the alkyd resin prepared as described in ExampleI which amounted to 5 grams was dissolved in 50 cc. of acetone and thesolution was divided into two parts. Nothing was added to one part ofthe solution while two drops Temperature Appearance aiter 3 days FilmNo.

Slightly tacky. Hard. Non-tacky, but softer than o. 2. Very hard.

The alkyd resin film was oxygen-convertible by contact with air and whenbaked at an elevated temperature in the presence of a di .er and air,was converted to a hard material.

I Example III For the purpose of further determining the dryingqualities of the alkyd resin described in Example I, films-oi the resinwere prepared with and without drier. Two drops of the siccativesolution described in Example II were mixed with about 4.9 grams of theresin. The conditions of hardeningtogether with the results obtained aretabulated below.

'Film No. Siccative Temperature ia in gfi of Very soft. 3 Tacky. l NoRoom 23.5 Do. 27.5 Do. 44 Do.

0 Very soit 3 Soft. 2 No 120C 7 Medium hard.

11 Hard.

0 Very soft. 3 Soft, tackfree. 3 Yes Room 23.6 Do. 1 27.5 Do. 44 Do.

0 Very soft. 3 Medium hard. 4 Yes 120C 7 Do.

11 Hard. I 27. Do.

Oxygen of the air combines with the resin when it hardens. This is seenfrom the results oi carbon and hydrogen analyses determined u-pon filmNos. 3 and 4 and given-in the following table:

Percentage Car- Hydro- Oxygen Increase Fl N incremein. 1m 0 bon gen(byditL) in oxygen oxygen Original Resin 63.5 5.5 31.0 a 01.5 5.4 33.12.1 6.7 4 62.1 5.5 32.4 1.4 4.5

Example IV About 29 parts'oi glycerol allyl ether and 29. parts ofphthalic anhydride were added to a vessel immersed in an oil bathmaintained at about 180 C. Nitrogen was passed through the reactionmixture and samples thereof were withdrawn at intervals fordetermination of the acid number. The results or these analyses aretabulated below:

Time from Start Acid Number 5 hours 110.8 24.5 .25 10.1

10 The alkyd resin obtained after 87.7 hours of heating was a darkbrown, gummy solid.

Example V About 22.9 parts 01' glycidol allyl ether and 296 parts ofphthalic anhydride were placed in a vessel equipped with a refiuxcondenser and agitator, and the vessel was immersed in an oil bath at100 C. Over a period of about 2 hours, the temperature was graduallyincreased to 180 C., which temperature was maintained over the course offormation of the resin. Nitrogen'was by-passed through the condenser tokeep oxygen away from thereaction mixture. After 6.25

hours, the acid number of the mixture was 91.8 and was decreased to 42.5after only 17 hours at which point the heating was discontinued. It isseen the alkyd resin was formed in much less time when glycidol allylether rather than glycerol allyl etherwas employed as reactant. Further,a more satisfactory color for the resin was obtained, it being an ambercolored, very viscous mass.

' Example VI A mixture of 25.4 parts of glycidol allyl ether and 29.6parts of phthalic anhydride was heated at 180 C. in a vessel fitted witha condenser through which nitrogen was passed. The acid number of theproduct was 109 after 5 hours heating and reached 43.1 in 12% hours.After heating about 22 hours the reaction mass was an insoluble gelindicating that the heating had been continued for too long a period sothat heat conversion of the alkyd resin to the gel form had occurred.

Example VII About 57 parts of .glycidol allyl ether and 74 parts ofDhthalic anhydride were placed in a vessel fitted with a refluxcondenser through which nitrogen was passed. To retard gelling, about 26parts of odorless kerosene boiling at 400 to 485 F. was added. Themixture was swept out with nitrogen and the temperature rose from 183 to220 C. After 6 hours heating, the acid number was 71 and 26 parts ofadditional glycidol allyl ether was added. The acid number was reducedto 46.2 after 13 hours when the'heating was stopped. The alkyd resinobtained was a heat:- and oxygen-convertible, dark brown, gummy mass.

The convertible alkyd resins of the invention are rendered insoluble andinfusible (converted to the C form) by subjection to the action'of heator oxygen or both. When contacted with oxygen, such as in application ofthe resin for surface coatings wherein they are spread on a surface inthe form of a film, siocatives are useful to accelerate the drying. Forthis purpose substances like lead, cobalt or manganese linoleates,resinates, naphthenates, etc. are incorporated in small amounts with theresin. The resins are also hardenable by the action of heat as by abaking treatment and for this purpose films of the resins when subjectedtotemperatures of about to C. are converted to the final state ofresiniileation. The alkyd resins are excellent for use with infra .redbaking methods where films are subjected to the heating action oi ini'ra red radiation.

The resins are useful in the variety of applications whenv applied insurface coating compositions like enamels. paints and the like. They areparticularly suitable owing to theirhigh' adhesiveness and protectiveresistance. When used in this'manner. the resins are employed in avehicle and formulated with various ingredients such as other "resins,plasticizers, pigments. etc. The resin is also useful for impregnatingmaterial such "as wood. cloth, paper. etc. Although, the resin is notwhat is termed a rapid ther'mosetting material, it may be used toiorm-articles by molding under the action or heat and pressure. Inconverting the resin by the action of heat, peroxide catalysts such asbensoyl peroxide, acetyl peroxide, ascaridole, etc., are usefullyincorporated with it.

The resins oi" the present invention which are polyesters, involveformation first of simple monoesters oi the unsaturatedmono-ether ofglycerol. Thus the reaction of a dlcarboxylic acid or the anhydride withglycerol monoailyl ether occurs.

o om=ch-om-o-cmcnon-om-o- HO-C- This mono-ester reacts with additionalphthalic anhydride to give the di-ester oi the formula HO-C Theexclusion principle of Carothers precludes formation of internal estersobtained by cyclization except in the cases where a 5 or 8 membered ringis possible such as in the case where oxalic acid is employed. forexample. In other words, the free acid group and free hydroxyl group ofthe mono-ester of glycerol allyl ether and phthalic anhydrlde will notreact togive an internal diester, but by reacting oxalic acid with.glycerol or glycidol mono-allyl ether the product of the followingformula can be produced.

0 H.=c HC rn-o-c BT 0 HC H:

These simple esters oi the invention are intermediate products of the,alkyd resins that are obtainable by discontinuing heating of thereaction mixture after formation of the simple esters form andseparating them from higher products which may be unavoidably producedand unreacted ether and acid. The simple esters are in themselves highlyuseful products in that besides being by action of heat reacted to theresin l. A process for the production oi a convertible alkyd resin whichcomprises heating and reacting in an inert atmosphere a compound fromthe group consisting oi dioarboxylic acids and dicarboxylic acidanhydrides wherein the earboxyi groups are the only reactive groups ofsaid compound, with about an equimolecular proportion to 20% excess of amono-alkenyl ether of glycerol wherein the alkenyl radical contains 3 to6 carbon atoms and has the oleilnic linkage between two carbon atoms,one or which is th'ecarbon atom of a terminal methylene group and theother'of which is linked directly to the saturatedcarbon atom having theetheral oxygen atom of the ether linked directly thereto, said reactionbeing-eiiected with the reaction mixture diluted with up to about 25%01' kerosene.

2. A process for the production 01 a convertible alkyd resinwhichcomprises heating and reacting in an inert atmosphere compound trom theoup consisting of dlcarboxylic acids and shearxylic acid anhydrideswherein the oarboxyl groups are the only reactive groups ofsaid'combound, with about an equimolecular proportion to 20% excess of amono-alkenyl ether of glycerol wherein the alkenyl radical containsB to8 carbon atoms and has the oleflnic linkage between two carbon atoms,one of which is the carbon atom of a terminal methylene group and theother 01' which is linked directly to the saturated carbon atom havingthe etheral oxygen .atom oi! said ether linked directly thereto.

3. An alkyd resin obtained by heating and reacting in an inertatmosphere a compound from the group consisting of dicarboxylic acidsand dicarboxylic acid anhydrides wherein the carboxyl groups are theonly reactive groups of said compound, with about an equimolecularproportion to 20% excess of a mono-alkenyl ether oi 'g'lycerol whereinthe alkenyl radical contains 3 to 8 carbon atoms and has the olefiniclinkage between two carbon atoms, one of which is the carbon atom of aterminal methylene group and the other of which is linked directlyto-the saturated carbon atom having the ethereal oxygen atom of saidether linked directly thereto.

4. A process for the production" of an alkyd npsin which comprisesheating and reacting in an inert atmosphere about an equimolecularproportion to 10% excess of glycerol mono-allyl ether with a compoundfrom the group consisting of dicarboxylic acids and dicarboxylic acidanhydrides wherein the carboxyl groups are the only reactive groups ofsaid compound.

5. An alkyd resin obtained by heating and reacting in an inertatmosphere about an equimolecular proportion to 10% excess of glycerolmono-allyl ether with a compound from the group consisting ofdicarboxylic acids and dicarboxylic acid anhydrides wherein the carboXyigroups are the only reactive groups of said compound.

6. A process for the production of an alkyd resin which comprisesheating and reacting in an inert atmosphere about an equimolecularproportion to 10% excess of glycerol mono-allyl ether with adicarboxylic acid anhydride wherein the mono-allyl ether with adicarboxylic acid anhy-.

dride wherein the carboxyl groups are the only reactive groups of saidanhydride.

8. A process for the production of an alkyd resin which comprisesheating and reacting in an inert atmosphere about an equimolecularproportion to excess of glycerol mono-allyl ether with phthalicanhydride wherein the carboxyl groups are the only reactive groups ofsaid anhydride.

9. An alkyd resin obtained by heating and reacting in an inertatmosphere about an equimolecular proportion to 10% excess of glycerolmono-allyi ether with phthalic anhydride wherein the carboxyl groups arethe only reactive groups of said anhydride.

10. A process for the production of an alkyd resin whichcomprisesheating and reacting in an inert atmosphere about anequimolecular proportion to 10% excess of glycerol mono-allyi ether withphthalic anhydride wherein the carboxyl groups are the only reactivegroups of said anhydride, said reaction being effected with the reactionmixture diluted with up to about 25% of kerosene.

11. A process for the production of an alkyd resin which comprisesheating and reacting in an inert atmosphere about an equimolecularproportion to 20% excess of glycerol mono-allyl ether with adicarboxylic acid wherein the carboxyl groups are the only reactivegroups of said acid.

12. An alkyd resin obtained by heating and reacting in an inertatmosphere about an equimolecular proportion to 20% excess of glycerolmonc-ailyl ether with a dicarboxylic acid wherein the carboxyl groupsare the only reactive groups of said acid.

13. A process for the production of an alkyd resin which comprisesheating and reacting in an inert atmosphere about an equimolecularproportion to 10% excess of glycerol mono-allyl ether with succinic acidwherein'the carboxyl groups are the only reactive groups of said acid.

14. An alkyd resin obtained by heating and reacting in an inertatmosphere about an equimolecular proportion to 10% excess of glycerolmono-allyl ether with succinic acid wherein the carboxyl groups are theonly reactive groups of said acid.

15. A process for the production of an alkydv resin which comprisesheating and reacting in an inert atmosphere about an e'quimolecularproportion to 10% excess of glycerol mono-allyl ether with diglycollicacid wherein the carboxyl groups are the only reactive groups of saidacid.

16. An alkyd resin obtained by heating and reacting in an inertatmosphere about an equimolecular proportion to 10% excess of glycerolmono-allyl ether with diglycollic acid wherein the carboxyl groups arethe only reactive groups of said acid.

THEODORE W. EVANS.

DAVID E. ADELSON.

REFERENCES. CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,152,683 Eichwald Apr. 4, 19392,399,214 Evans et a1 Apr. 30, 1946

